Method for manufacturing liquid injecting head

ABSTRACT

The present invention provides a method for manufacturing a liquid injecting head, in which liquid flow paths are defined by combining an element substrate having a plurality of discharge energy generating elements for applying discharge energy to liquid with a nozzle member having a plurality of liquid discharge nozzle grooves, which method comprises a step for preparing at least one material common to the element substrate as a base material of the nozzle member, a step for forming etching mask layers on a first surface of the base material of the nozzle member in which the nozzle grooves are formed and a second surface opposite to the first surface, a step for forming a recessed portion in the second surface of the base material by patterning the mask layer on the second surface of the base material and by effecting etching via the mask layer of the second surface, and a step for forming the nozzle grooves in the base material and for communicating the recessed portion with the nozzle grooves by patterning the mask layer on the first surface of the base material and by effecting etching via the mask layer of the first surface and the mask layer of the second surface.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The present invention relates to a method for manufacturing aliquid injecting head used with a liquid injecting system for injectingliquid from a liquid discharge nozzle as a liquid droplet.

[0003] 2. Related Background Art

[0004] A liquid injecting head used with a liquid injecting system (inkjet system) includes a plurality of liquid discharge nozzles fordischarging liquid such as ink, liquid supply paths communicated withthe respective liquid discharge nozzles, and discharge energy generatingelements (for example, electrical/thermal converting elements)associated with the respective liquid discharge nozzles so that, byapplying a drive signal corresponding to discharge information to thedischarge energy generating element to afford discharge energy to liquidwithin the liquid discharge nozzle associated with the discharge energygenerating element, the liquid is discharged from a minute dischargeport of the liquid discharge nozzle as a flying liquid droplet, therebyeffecting the recording.

[0005] As liquid discharge heads of this kind and nozzle memberstherefor, various techniques have been proposed, and variousmanufacturing method therefor have also been proposed. Now, an exampleof the conventional liquid discharge head and nozzle member thereforwill be described with reference to FIGS. 11 and 12. FIG. 11 is a viewshowing a liquid discharge head and a nozzle member disclosed inJapanese Patent Application Laid-open No. 6-31918 (1994), for example,wherein a nozzle member 101 is formed from a silicon wafer cut andpolished to have a surface having crystal <100> face. The nozzle memberincludes a through opening 102 for supplying liquid and liquid dischargenozzles 103. A heater board (element substrate) 105 comprises siliconchips on which plural electrical/thermal converting elements (referredto as “heaters” hereinafter) 106 as discharge energy generating elementsare provided. The nozzle member 101 and the heater board 105 are joinedor adhered to each other so that the nozzles 103 are opposed to theheaters 106, and thin or fine nozzles each having a triangularcross-section are defined between the nozzles 103 and a surface of theheater board 105, and the heaters 106 are included in the respectivenozzles 103.

[0006] The nozzle member 101 is manufactured as follows. That is to say,an inorganic film made of SiO₂ is formed on the surface of the siliconwafer constituting the nozzle member 101 by a film forming method suchas thermal oxidation of CVD, and resist material of an organic film isformed on the nozzle surface by a spin-coat method. Then, patterningcorresponding to shapes of the nozzles 103 and the through opening 102is effected, and, thereafter, anisotropical wet etching is effectedwhile immersing the nozzle member into etching liquid such as KOH orTMAH. As a result, the etching growths along <111> face of silicon, and,when the silicon wafer having the surface of <100> face is used, sincethe <111> face is inclined by 54.7 degrees with respect to the surface,the nozzles 103 and the through opening 102 are formed as shapes asshown in FIGS. 11 and 12.

[0007] When the liquid injecting head is formed by joining or adheringthe nozzle member 101 formed in this way to the heater board 105, sincethere remains a wall portion 110 between the nozzles 103 and the throughopening 102 in the nozzle member 101, flow paths for liquid cannot bereserved. To reserve such flow paths, as shown in FIG. 12, flow pathwalls 107 are formed on the heater board 105 by patterning polyimidematerial, thereby reserving liquid supply paths as shown by the arrow108.

[0008] In the liquid injecting head shown in FIGS. 11 and 12, liquidsuch as ink is supplied from a liquid tank (not shown) and is directedinto the through opening 102 as the liquid supply path and reaches thenozzles 103 through the aforementioned liquid supply paths. Theplurality of heaters 106 provided on the heater board 105 are controlleda control circuit (not shown) so that the heater 106 is selectivelyenergized in response to recording information. The heater 106 energizedin response to the recording information generates heat to heat theliquid within the corresponding nozzle 103, and the heated liquid isboiled when exceeds a certain critical temperature, thereby forming abubble. Due to increase in volume caused by the formation of the bubble,a part of the liquid is forcibly pushed out from the nozzle 103 to flyonto a recording medium such as paper. By repeating such operations, arecorded image is completed.

[0009] In the above-mentioned conventional technique, by using thesilicon wafer having the surface of <100> face as the nozzle member,although there is provided advantages that a depth can be adjusted byconfiguration of patterning since the etching grows obliquely and thatthe nozzles and the through opening can be formed by single etching, asshown in FIG. 12, since the wall portion 110 remains between the nozzles103 and the through opening 102, the flow path walls 107 must be formedon the heater board 105 by patterning the polyimide material to reservethe liquid supply paths shown by the arrow 108 in FIG. 12, which makesmanufacturing processes of the heater board complicated.

[0010] Further, since the shape of each nozzle 103 has the triangularcross-section as shown in FIG. 11, a wall thickness between the nozzles103 is increased, which worsens efficiency for forming the nozzles andaffects a bad influence upon high density arrangement of nozzles.

[0011] Furthermore, in the liquid injecting head in which the heatersare used as the discharge energy generating elements, to solve a problemthat a force of the bubble for discharging the liquid escapes throughthe through opening, as shown in FIG. 13, there has been proposed amethod in which a valve 109 is provided above each heater 106 to enhancethe liquid discharging efficiency. That is to say, the valve 109 servesto be moved upwardly by the bubble force when the bubble is generated bythe heating of the heater 106 and to prevent the bubble from escapingtoward the through opening 102. However, in the case there the nozzle103 has the triangular cross-section, when the valve 109 is movedupwardly, the valve is apt to be contacted with the walls of the nozzle103, and, in order to prevent the valve 109 from contacting with thewalls of the nozzle, a nozzle width must be increased excessively, whichaffects a bad influence upon the high density arrangement of nozzles.

[0012] Further, there have also been proposed methods for nozzles byworking material other than silicon, and, according to such methods,although there is provided an advantage that the nozzles can be formedas free configurations by using resin and the like, when the number ofnozzles is increased to lengthen the recording head, due to differencein thermal expansion rate between the nozzle member and the heaterboard, good adhesion between the nozzle member and the heater boardcannot be achieved, which leads in limitation of the dimension length ofthe liquid injecting head.

SUMMARY OF THE INVENTION

[0013] The present invention is made in consideration of theabove-mentioned conventional drawbacks, and an object of the presentinvention is to provide a method for manufacturing a liquid injectinghead, in which a liquid injecting head suitable for high densityarrangement of nozzles and suitable for lengthening the head can bemanufactured by forming a plurality of nozzles each having a rectangularcross-section by effecting anisotropical etching on a member in whichliquid discharge nozzles are to be formed.

[0014] To achieve the above object, according to the present invention,there is provided a method for manufacturing a liquid injecting head, inwhich liquid flow paths are defined by combining an element substratehaving a plurality of discharge energy generating elements for applyingdischarge energy to liquid with a nozzle member having a plurality ofliquid discharge nozzle grooves, which method comprises a step forpreparing at least one material common to the element substrate as abase material of the nozzle member, a step for forming etching masklayers on a first surface of the base material of the nozzle member inwhich the nozzle grooves are formed and a second surface opposite to thefirst surface, a step for forming a recessed portion in the secondsurface of the base material by patterning the mask layer on the secondsurface of the base material and by effecting etching via the mask layerof the second surface, and a step for forming the nozzle grooves in thebase material and for communicating the recessed portion with the nozzlegrooves by patterning the mask layer on the first surface of the basematerial and by effecting etching via the mask layer of the firstsurface and the mask layer of the second surface.

[0015] In the liquid injecting head manufacturing method according tothe present invention, it is preferable that a silicon wafer having asurface of <110> face is used as the material of the nozzle member.

[0016] In the liquid injecting head manufacturing method according tothe present invention, it is preferable that an etching amount t ofanisotropical etching for forming the recessed portion satisfies arelationship tw>t>tw−tn when it is assumed that a thickness of thenozzle member (silicon wafer) is tw and a depth of the nozzle groove istn, and, in the manufacturing method in which the nozzle grooves and aliquid chamber are formed simultaneously by anisotropical etching, it ispreferable that an etching amount t of anisotropical etching for formingthe liquid supply paths satisfies a relationship tw >t>tw−2×tn when itis assumed that a thickness of the nozzle member (silicon wafer) is twand a depth of the nozzle groove is tn.

[0017] According to the liquid injecting head manufacturing method ofthe present invention, high density arrangement of nozzles can bepermitted, and an elongated liquid injecting head can easily bemanufactured.

[0018] Further, an elongated high density liquid injecting head canstably be manufactured without increasing alignment accuracy ofpatterning.

[0019] Furthermore, by forming the nozzle member by using the samesilicon as the heater board, distortion due to heat does not occurbetween the nozzle member and the heater board, with the result goodadhesion between the nozzle member and the heater board can bemaintained and the liquid injecting head can be made longer.

BRIEF DESCRIPTION OF THE DRAWINGS

[0020]FIG. 1 is a schematic perspective view of a liquid injecting headmanufactured in accordance with a first embodiment of a liquid injectinghead manufacturing method of the present invention;

[0021]FIGS. 2A, 2B and 2C are views showing a nozzle member constitutingthe liquid injecting head manufactured in accordance with the firstembodiment of the present invention, where FIG. 2A is a plan view of thenozzle member looked at from a nozzle forming surface side, FIG. 2B is aside view of the nozzle member, and FIG. 2C is a sectional view takenalong the line 2C-2C in FIG. 2A;

[0022]FIGS. 3A, 3B, 3C, 3D, 3E, 3F and 3G are views showingmanufacturing steps for the nozzle member according to the firstembodiment of the present invention;

[0023]FIGS. 4A, 4B, 4C, 4D, 4E, 4F and 4G are views showingmanufacturing steps for a nozzle member according to an alteration ofthe first embodiment of the present invention;

[0024]FIG. 5 is a sectional view of a liquid injecting head in which avalve for improving discharge efficiency is added to the liquidinjecting head manufacturing in accordance with the first embodiment ofthe present invention;

[0025]FIG. 6 is a schematic perspective view of a liquid injecting headmanufactured in accordance with a second embodiment of a liquidinjecting head manufacturing method of the present invention;

[0026]FIGS. 7A, 7B and 7C are views showing a nozzle member constitutingthe liquid injecting head manufactured in accordance with the secondembodiment of the present invention, where FIG. 7A is a plan view of thenozzle member looked at from a nozzle forming surface side, FIG. 7B is aside view of the nozzle member, and FIG. 7C is a sectional view takenalong the line 7C-7C in FIG. 7A;

[0027]FIGS. 8A, 8B, 8C, 8D, 8E, 8F and 8G are views showingmanufacturing steps for the nozzle member according to the secondembodiment of the present invention;

[0028]FIGS. 9A, 9B, 9C, 9D, 9E, 9F and 9G are views showingmanufacturing steps for a nozzle member according to an alteration ofthe second embodiment of the present invention;

[0029]FIG. 10 is a sectional view of a liquid injecting head in which avalve for improving discharge efficiency is added to the liquidinjecting head manufactured in accordance with the second embodiment ofthe present invention;

[0030]FIG. 11 is a schematic perspective view of a conventional liquidinjecting head;

[0031]FIG. 12 is a schematic perspective view of the liquid injectinghead shown in FIG. 11; and

[0032]FIG. 13 is a schematic sectional view of a liquid injecting headin which a valve for improving discharge efficiency is added to theliquid injecting head shown in FIG. 11.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0033] The present invention will now be explained in connection withembodiments thereof with reference to the accompanying drawings.

[0034]FIG. 1 is a schematic perspective view of a liquid injecting headmanufactured in accordance with a first embodiment of a liquid injectinghead manufacturing method of the present invention, and FIGS. 2A to 2Care views showing a nozzle member constituting the liquid injecting headmanufactured in accordance with the first embodiment of the presentinvention, where FIG. 2A is a plan view of the nozzle member looked atfrom a nozzle forming surface side, FIG. 2B is a side view of the nozzlemember, and FIG. 2C is a sectional view taken along the line 2C-2C inFIG. 2A.

[0035] In FIG. 1 and FIGS. 2A to 2C, a nozzle member 1 is formed from asilicon wafer having a surface of <110> face, and the nozzle member 1 isprovided with a through opening 2 as a liquid supply path for supplyingliquid, and a plurality of liquid discharge nozzles (or nozzle grooves)3 and is joined or adhered to an element substrate (referred to as“heater board” hereinafter) 5 on which a plurality of heaters 6 asdischarge energy generating elements are provided.

[0036] The through opening 2 and the nozzles 3 are formed to haverectangular cross-sections by effecting anisotropical etching by usingthe silicon wafer having the surface of <110> face as material of thenozzle member 1, which cross-sections are different from triangular ortrapezoidal cross-sections of the conventional nozzles and throughopening. By using the nozzle member 1 in which the nozzles 3 have therectangular cross-section in this way, since a wall thickness betweenthe nozzles 3 can be thinned, high density arrangement of nozzles 3 caneasily be realized, and, since the nozzles 3 and the through opening 3are interconnected within the nozzle member 1, it is not required thatliquid supply paths be reserved by forming walls on the heater board 5.That is to say, unlike to the conventional case, when the nozzle member1 is closely joined to the heater board 5 having no special flow pathmembers made of polyimide and liquid is supplied from a liquid tank (notshown) into the through opening 2, the nozzles 3 are filled with theliquid by a capillary phenomenon, and, when the heater 6 on the heaterboard 5 is energized under the control of a control circuit (not shown),the liquid is bubbled and is discharged from a discharge port at an endof the nozzle 3.

[0037] Next, a method for manufacturing the nozzle member 1 will befully described.

[0038] In general, it is known that, when silicon is subjected to wetetching by using etching liquid such as TMAH or KOH, an anisotropicaletching phenomenon in which etching grows along <111> crystal faceoccurs. If such wet etching is effected on the silicon wafer having thesurface of <100> face, since the <111> face is inclined by 54.7 degreeswith respect to the <100> face, the shapes as described in connectionwith the conventional technique will be obtained. However, in case ofthe silicon wafer having the surface of <110> face, since the <111> faceis perpendicular to the surface, the nozzles having vertical walls asshown in FIGS. 1 and 2A to 2C can be formed.

[0039] In this case, however, since the longer the etching time thegreater a depth of a groove (ultimately forming a through hole), thedepth of the groove cannot be controlled by the mark configuration,unlike to the conventional case. That is to say, the nozzles and thethrough opening cannot be formed by single etching, and, thus,patterning of mask and etching of silicon must be effected two times.Although the depth of the nozzle is varied in dependence upon density ofnozzles, since the nozzle depth is generally 10 μm to several hundredsof μm, for example, if the nozzles are firstly formed, although thenozzles must be protected by coating resist on the nozzles when thethrough opening is formed, it is difficult to coat the resist on thenozzles uniformly, thereby arising a problem regarding the protection ofthe nozzles. On the other hand, if the through opening is firstlyformed, the patterning of nozzle surface will become very difficult.

[0040] Now, manufacturing steps for the nozzle member according to afirst embodiment will be explained with reference to FIGS. 3A to 3G.

[0041] In FIG. 3A, a silicon (Si) wafer 10 constituting material for thenozzle member has a surface of <110> face. As shown in FIG. 3B, films11, 12 of silicon dioxide (SiO₂) are formed on both surfaces of thesilicon wafer 10 by a film forming method such as thermal oxidation orCVD. Incidentally, the silicon dioxide serves as a mask layer when thesilicon is subjected to anisotropical etching. Then, as shown in FIG.3C, patterning corresponding to the shape of the through opening iseffected on the SiO₂ film 11 opposite to the nozzle forming surface by anormal photo-lithography technique. Then, the anisotropical etching iseffected while immersing the wafer into etching liquid such as TMAH. Theetching grows from the patterning portion, thereby forming a deep hole 2a, as shown in FIG. 3D. In this case, it is important that the hole doesnot become a through hole by controlling the etching condition. Namely,if the hole 2 a becomes the through hole and only the thin SiO₂ film 12remains on the nozzle forming surface, it is impossible to maintain thewafer surface at the nozzle forming surface side flat, with the resultthat it becomes difficult to effect resist coating and exposure in thenext nozzle formation. Thus, it is important that the silicon remains bya small thickness smaller than a depth of the nozzle. That is to say, anetching amount t of the anisotropical etching has a value satisfying arelationship tw >t>tw−tn when it is assumed that a thickness of thesilicon wafer (nozzle member) is tw and a depth of the nozzle 3 is tn.

[0042] Then, resist material (not shown) is coated on the SiO₂ film 12at the nozzle forming surface side, and patterning corresponding to thenozzle configuration is effected by dry etching (FIG. 3E). In this case,as mentioned above, since the nozzle forming surface side is kept flat,the coating of the resist material and the patterning corresponding tothe nozzle configuration can be performed easily. Then, by immersing thesilicon wafer into anisotropical etching liquid again, the nozzleportion is etched and, at the same time, etching for the holes 2 a iscontinued from the opposite side. As a result, when the nozzle 3 isformed, the hole 2 a reaches the nozzle forming surface to form thethrough opening 2 communicated with the nozzle 3 (FIG. 3F). Lastly, byremoving the SiO₂ films 11, 12 remaining on both surfaces of the siliconwafer 10, a nozzle member having the nozzle 3 and the through opening 2as shown in FIG. 3G is completed.

[0043] Next, an alteration of the nozzle member manufacturing stepsaccording to the illustrated embodiment will be explained with referenceto FIGS. 4A to 4G. In this alteration, steps shown in FIGS. 4A to 4D arethe same as the aforementioned steps shown in FIGS. 3A to 3D. Further,in the step shown in FIG. 3E, while the dry etching was effected whenthe patterning of the SiO₂ film 12 was performed, this alterationdiffers from the illustrated embodiment in that, in a step shown in FIG.4E, wet etching is effected. That is to say, while the SiO₂ film 11 wasremained on the surface opposite to the nozzle forming surface in thestep shown in FIG. 3E, in the step shown in FIG. 4E, such a film 11 isremoved. The reason is that, since the SiO₂ film 11 on the surfaceopposite to the nozzle forming surface is once subjected to thepatterning for formation of the through opening and thus it is difficultto coat the resist thereon to protect the film, when the silicon waferis immersed into the etching liquid in order to effect the patterning ofthe SiO₂ film 12 at the nozzle forming surface side, the SiO₂ film 11 onthe surface opposite to the nozzle forming surface is etchedsimultaneously. Accordingly, in the anisotropical etching for formationof the nozzle (FIG. 4F), at the same time when the nozzle is formed,silicon at the opposite side is also etched. However, this opposite sidedoes not relate to the discharge property directly, and, since it isimportant that the liquid from the liquid tank (not shown) be suppliedwithout leakage, even when the nozzle member is totally thinned more orless, there is no problem regarding function. In this way, in thisalteration, the wet etching is effected as the patterning of silicondioxide, thereby enhancing the productivity.

[0044] Further, in the first embodiment and the alteration thereofaccording to the present invention, since the same silicon as the heaterboard is used as the material of the nozzle member, even when the numberof nozzles is increased to make the liquid injecting head longer, theadhesion (close contact) between the nozzle member and the heater boardis maintained and distortion due to heat does not occur.

[0045] Furthermore, the nozzle member in the first embodiment and thealteration thereof according to the present invention is also effectivewhen a valve is provided in the nozzle to enhance the dischargingefficiency. That is to say, as shown in FIG. 5, in a case where a valve9 is provided above the heater 6, since the nozzle 3 has the rectangularcross-section, when the valve 9 is moved upwardly, the valve does notcontact with the walls of the nozzle 3. Thus, since a width of thenozzle 3 may be slightly greater than a width of the valve 9, highdensity arrangement of nozzles can be achieved while maintaining highdischarging efficiency.

[0046] Next, a second embodiment of a liquid injecting headmanufacturing method according to the present invention will beexplained with reference to FIGS. 6 to 10. FIG. 6 is a schematicperspective view of a liquid injecting head manufactured in accordancewith a second embodiment of a liquid injecting head manufacturing methodof the present invention, and FIGS. 7A to 7C are views showing a nozzlemember constituting the liquid injecting head manufactured in accordancewith the second embodiment of the present invention, where FIG. 7A is aplan view of the nozzle member looked at from a nozzle forming surfaceside, FIG. 7B is a side view of the nozzle member, and FIG. 7C is asectional view taken along the line 7C-7C in FIG. 7A.

[0047] In FIG. 6 and FIGS. 7A to 7C, a nozzle member 21 is formed from asilicon wafer having a surface of <110> face, and the nozzle member 21is provided with a through opening 2 as a liquid supply path forsupplying liquid, a plurality of liquid discharge nozzles (or nozzlegrooves) 23 and a liquid chamber 24 (refer to FIG. 7A) for reserving theliquid to stably supply the liquid into the nozzles 23 and is joined oradhered to a heater board 25 on which a plurality of heaters 26 asdischarge energy generating elements are provided.

[0048] The through opening 2, nozzles 3 and liquid chamber 24 are formedto have rectangular cross-sections by effecting anisotropical etching byusing the silicon wafer having the surface of <110> face as material ofthe nozzle member 1. In general, it is known that, when silicon issubjected to wet etching by using etching liquid such as TMAH or KOH,etching grows along <111> crystal face. Since the <111> face isperpendicular to the <110> face, the nozzles having vertical walls asshown in FIGS. 6 and 7A to 7C can be formed. Further, by forming theliquid chamber 24 by anisotropical etching simultaneously with thenozzles 23, although a depth of the liquid chamber is substantially thesame as depths of the nozzles 23, since the liquid chamber does not havewalls such as those of the nozzles, the depth of the liquid chamberbecomes slightly greater than the depths of the nozzles.

[0049] Next, manufacturing steps for the nozzle member according to thesecond embodiment will be explained with reference to FIGS. 8A to 8G.

[0050] In FIG. 8A, a silicon (Si) wafer 30 constituting material for thenozzle member has a surface of <110> face. As shown in FIG. 8B, films31, 32 of silicon dioxide (SiO₂) are formed on both surfaces of thesilicon wafer 30 by a film forming method such as thermal oxidation orCVD. Then, as shown in FIG. 8C, patterning corresponding to the shape ofthe through opening is effected on the SiO₂ film 31 opposite to thenozzle forming surface by a normal photo-lithography technique. Then,the anisotropical etching is effected while immersing the wafer intoetching liquid such as TMAH. The etching grows from the patterningportion, thereby forming a deep hole 22 a, as shown in FIG. 8D. In thiscase, it is important that the hole does not become a through hole bycontrolling the etching condition. Namely, if the hole 22 a becomes thethrough hole and only the thin SiO₂ film 32 remains on the nozzleforming surface, it is impossible to maintain the wafer surface at thenozzle forming surface side flat, with the result that it becomesdifficult to effect resist coating and exposure in the next nozzleformation. Thus, the silicon layer remains by such as amount that thewafer surface at the nozzle forming surface side can be kept flat. Thatis, the silicon layer having a thickness smaller than twice of a depthof the nozzle, as will be described later.

[0051] Then, resist material (not shown) is coated on the SiO₂ film 32at the nozzle forming surface side, and patterning corresponding toconfigurations of the nozzle 23 and the liquid chamber 24 is effected bydry etching (FIG. 8E). In this case, since the nozzle forming surfaceside is kept flat, the coating of the resist material and the patterningcorresponding to the configurations of the nozzle and the liquid chambercan be performed easily. Then, by immersing the silicon wafer intoanisotropical etching liquid again, the nozzle and liquid chamberportions are etched and, at the same time, etching for the holes 22 a iscontinued from the opposite side. As a result, when the nozzle 23 isformed, the hole 22 a reaches the nozzle forming surface to form thethrough opening 22 communicated with the nozzle 23 through the liquidchamber 24 (FIG. 8F). In this case, since the liquid chamber portiondoes not have the wall such as the wall of the nozzle, the etching speedof the liquid chamber becomes greater than that of the nozzle, and,thus, the depth of the liquid chamber becomes slightly greater than thedepth of the nozzle. Here, regarding a relative position of the throughopening 22 with respect to the liquid chamber 24, since it is importantthat the liquid chamber 24 is merely communicated with the throughopening 22, so long as the through opening 22 sufficiently smaller thanthe dimension of the liquid chamber 24, the alignment accuracy is notrequired to be severe. By forming the nozzle 23 and the liquid chamber24 simultaneously, the length of the nozzle can be reserved and thethrough opening 22 can surely be communicated with the liquid chamber24. Further, at an area where the through opening 22 is communicatedwith the liquid chamber 24, since the etching grows from both sides, thethickness of the silicon to be remained (not to form the hole 22 a asthe through opening) in the anisotropical etching step shown in FIG. 8Dcan be made smaller than twice of the depth of the nozzle. That is tosay, an etching amount t of the anisotropical etching may have a valuesatisfying a relationship tw >t>tw−2×tn when it is assumed that athickness of the silicon wafer (nozzle member) 30 is tw and the depth ofthe nozzle 23 is tn.

[0052] In this way, in the second embodiment, a problem that the nozzlesmay not be communicated with the through opening due to mis-alignmentcaused when the patterning is effected on both surfaces of the siliconwafer to form the nozzles 23 and the through opening 22 respectively,and a problem that the lengths of the nozzles are reduced due toexcessive overlap can be eliminated.

[0053] After the nozzles 23, liquid chamber 24 and through opening 22were formed in this way, by removing the SiO₂ films 31, 32 remaining onboth surfaces of the silicon wafer 30, the nozzle member as shown inFIG. 8G is completed.

[0054] By using the nozzle member manufactured in accordance with thesecond embodiment, since a wall thickness between the nozzles can bethinned, high density arrangement of nozzles can easily be realized,and, since the nozzles and the through opening are interconnected withinthe nozzle member, it is not required that liquid supply paths bereserved by forming walls on the heater board. That is to say, as shownin FIG. 6, when the nozzle member 21 is closely joined to the heaterboard 25 having no special flow path members made of polyimide andliquid is supplied from a liquid tank (not shown) into the throughopening 22, the nozzles 23 are filled with the liquid through the liquidchamber 24 by a capillary phenomenon. Further, since the correct nozzlelength can be reserved without increasing the alignment accuracy of thepatterning on both surface, the stable liquid discharging can always beperformed. Incidentally, although the rectangular grooves can be formedby dry etching in the nozzle forming step shown in FIG. 8F, wet etchingis preferable in consideration of productivity.

[0055] Next, an alteration of the nozzle member manufacturing stepsaccording to the illustrated embodiment will be explained with referenceto FIGS. 9A to 9G. In this alteration, steps shown in FIGS. 9A to 9D arethe same as the aforementioned steps shown in FIGS. 8A to 8D. Further,in the step shown in FIG. 8E, while the dry etching was effected whenthe patterning of the SiO₂ film 32 was performed, this alterationdiffers from the illustrated embodiment in that, in a step shown in FIG.9E, wet etching is effected. That is to say, while the SiO₂ film 31 wasremained on the surface opposite to the nozzle forming surface in thestep shown in FIG. 8E, in the step shown in FIG. 9E, such a film 31 isremoved. The reason is that, since the SiO₂ film 31 on the surfaceopposite to the nozzle forming surface is once subjected to thepatterning for formation of the through opening and thus it is difficultto coat the resist thereon to protect the film, when the silicon waferis immersed into the etching liquid in order to effect the patterning ofthe SiO₂ film 32 at the nozzle forming surface side, the SiO₂ film 31 onthe surface opposite to the nozzle forming surface is etchedsimultaneously. Accordingly, in the anisotropical etching for formationof the nozzle (FIG. 9F), at the same time when the nozzle is formed,silicon at the opposite side is also etched. However, this opposite sidedoes not relate to the discharge property directly, and, since it isimportant that the liquid from the liquid tank (not shown) be suppliedwithout leakage, even when the nozzle member is totally thinned more orless, there is no problem regarding function. In this way, in thisalteration, the wet etching is effected as the patterning of silicondioxide, thereby further enhancing the productivity.

[0056] As mentioned above, also in the second embodiment and thealteration thereof according to the present invention, high densityarrangement of nozzles can be realized, and, since the same silicon asthe heater board is used as the material of the nozzle member, even whenthe number of nozzles is increased to make the liquid injecting headlonger, the adhesion (close contact) between the nozzle member and theheater board is maintained and distortion due to heat does not occur.Further, the nozzle member in the second embodiment and the alterationthereof according to the present invention is also effective when avalve is provided in the nozzle to enhance the discharging efficiency.That is to say, as shown in FIG. 10, in a case where a valve 29 isprovided above the heater 26, since the nozzle 23 has the rectangularcross-section, when the valve 29 is moved upwardly, the valve does notcontact with the walls of the nozzle 23. Thus, since a width of thenozzle 23 may be slightly greater than a width of the valve 29, highdensity arrangement of nozzles can be achieved while maintaining highdischarging efficiency.

[0057] As mentioned above, according to the present invention, since thevertical nozzle walls can be formed by using the silicon as the materialof the nozzle member of the liquid injecting head, an elongated liquidinjecting head having high density arrangement of nozzles can easily bemanufactured.

[0058] Further, by manufacturing the nozzle member by using the samesilicon as the heater board, distortion due to heat between the nozzlemember and the heater board can be prevented, with the result that theclose contact between the nozzle member and the heater board can bemaintained, thereby providing an elongated liquid injecting head.

What is claimed is:
 1. A method for manufacturing a liquid injectinghead, in which liquid flow paths are defined by combining an elementsubstrate having a plurality of discharge energy generating elements forapplying discharge energy to liquid with a nozzle member having aplurality of liquid discharge nozzle grooves, comprising the steps of:preparing at least one material common to said element substrate as abase material of said nozzle member; forming etching mask layers on afirst surface of the base material of said nozzle member in which saidnozzle grooves are formed and a second surface opposite to said firstsurface; forming a recessed portion in said second surface of the basematerial by patterning said mask layer on said second surface of thebase material and by effecting etching via said mask layer of saidsecond surface; and forming said nozzle grooves in the base material andfor communicating said recessed portion with said nozzle grooves bypatterning said mask layer on said first surface of the base materialand by effecting etching via said mask layer of said first surface andsaid mask layer of said second surface.
 2. A method according to claim1, wherein an etching amount t of etching for forming said recessedportion satisfies a relationship tw >t >tw - tn when it is assumed thata thickness of said nozzle member is tw and a depth of said nozzlegroove is tn.
 3. A method according to claim 1, wherein said nozzlemember is a silicon substrate formed to have a surface of <110> crystalface orientation, and etching for the base material of said nozzlemember is anisotropical etching directing perpendicular to a surface ofthe base material.
 4. A method according to claim 3, wherein said masklayer is constituted by a silicon dioxide film.
 5. A method formanufacturing a liquid injecting head, in which liquid flow paths aredefined by combining an element substrate having a plurality ofdischarge energy generating elements for applying discharge energy toliquid with a nozzle member having a plurality of liquid dischargenozzle grooves and a liquid chamber communicated with said nozzlegrooves, comprising the steps of: preparing at least one material commonto said element substrate as a base material of said nozzle member;forming etching mask layers on a first surface of the base material ofsaid nozzle member in which said nozzle grooves are formed and a secondsurface opposite to said first surface; forming a recessed portion insaid second surface of the base material by patterning said mask layeron said second surface of the base material and by effecting etching viasaid mask layer of said second surface; and forming said nozzle groovesand said liquid chamber in the base material and for communicating saidrecessed portion with said liquid chamber by patterning said mask layeron said first surface of the base material and by effecting etching viasaid mask layer of said first surface and said mask layer of said secondsurface.
 6. A method according to claim 5, wherein an etching amount tof etching for forming said recessed portion satisfies a relationship tw>t>tw−2×tn when it is assumed that a thickness of said nozzle member istw and a depth of said nozzle groove is tn.
 7. A method according toclaim 5, wherein said nozzle member is a silicon substrate formed tohave a surface of <110> crystal face orientation, and etching for thebase material of said nozzle member is anisotropical etching directingperpendicular to a surface of the base material.
 8. A method accordingto claim 7, wherein said mask layer is constituted by a silicon dioxidefilm.